Fire hose nozzles are used by fire fighters for supplying water or other liquids to extinguish fires. A common method of extinguishing fires is to direct a flow of liquid, usually water, onto the fire and often the surrounding area. The flow is typically delivered in a deluge, also known as a smooth bore or in a fog. The deluge or smooth bore provides a straight and solid stream, with maximum reach and penetration. The fog provides a pattern which can be a straight, aspirated spray or a wide, aspirated spray with less reach and penetration than a deluge.
A deluge can be delivered in a relatively precise area thus providing a maximum amount of water into a specific location. The flow rate may have to be reduced, or increased, depending on the changing character of the fire.
Fire fighters may use the fog to cover a wider area and without the force of a deluge which might scatter burning materials before they are extinguished, thus spreading a fire. They may also use the spray in a very wide pattern to create a shield from the intense heat of a fire. The wide fog pattern also creates a back draft which brings cooler, cleaner air from behind the fire fighter. A wide fog will more quickly lower the heat of a fire by flashing into steam.
Fire fighters may ideally need both flow types for the same fire and may prefer to move from deluge to fog and back. To accomplish this it is necessary to stop the flow and change nozzles.
Certain nozzles in the prior art, hereinafter referred to as combination nozzles, include both a deluge and a spray. The outer fog, which is always a wide pattern, deprives the fire of heat by evaporating water into steam, while the deluge maintains a high penetration full stream flow to the source of the fire. Combination nozzles of the prior art have a fixed fog pattern around a fixed deluge. They cannot produce a straight fog spray, nor can the fog and deluge operate independently of each other.
Combination nozzles of the prior art were intended to overcome the limitations of having to change single nozzles or use two different hoses simultaneously when two patterns were needed. However, combination nozzles of the prior art have several drawbacks. The flow is altered when additional streams are enabled. The prior art combination nozzles increase the area of discharge, and therefore the flow rate, force, pressure and nozzle reaction. An increase in force may be more than a fire fighter using such a nozzle can safely handle.
Changes in source pressure can cause a sudden increase in flow rate, force and nozzle reaction with either single or combination nozzles of the prior art. This can occur when multiple lines are being run from a single pump or when other lines are shut down quickly. Also, combination nozzles of the prior art may produce weak sprays due to insufficient pressure when both tips are in use.
Thus there exists a need for an apparatus and method which permits quick, efficient and convenient operation of a fire hose nozzle in deluge mode, fog mode, or both, and which maintains a constant flow when changing from deluge or fog to both modes or when supply pressure changes.